A Real-Time X-Ray Topography System

Real-time or “live” topography of single-crystalline solids is a direct method to image the fine structure within Laue diffraction spots being generated by deviations from perfection of a crystal lattice, for example, by dislocations. We describe a direct display system which is operative at this institution. A 6-μm-thick fluorescent screen converts the X-ray pattern into an optical image. This optical picture is imaged onto the target of a low-light-level television camera through a magnifying optical system. A digital image processing equipment integrates the video pictures. Time resolution can be thus varied between 20 ms and 5 s in order to achieve a better signal-to-noise ratio, and, therefore, a better spatial resolution. The detector system has a spatial resolution of about 10 μm. The added and stored picture is rendered visible on a television monitor.

A movie shows at first a comparison between integrated and direct pictures. Then, a dislocation array is created above 1273 K by the strain field of an indentation. The indentation is made at room temperature on the silicon specimen. Last, we show the high-temperature behavior of strain fields at the edges of oxide layers grown on silicon substrates.